The present invention is generally directed to wicks. In particular, it is directed at wicks where the capillary is formed by fibrous materials. More particularly, the present invention is directed to composite bonded fiber wick structures that displace a specific amount of fluid relative to an amount that is initially absorbed.
It is known in the art to manufacture isotropic wicks for a variety of applications. Such isotropic wicks are generally three-dimensional, porous, bonded fiber elements that may serve to wick a fluid from a first location to a second location. These wicks may be used in diverse applications, such as in air freshener devices, lighters, writing instruments, and for a variety of biological fluids, such as urine and/or blood. Such wicks are disclosed in U.S. patent application Ser. No. 11/333,499, which is herein incorporated by reference in its entirety.
When such bonded fiber wicks are used in air freshener devices, the wick is often immersed in a fluid (typically containing a fragrance), and by capillary force the fluid is drawn into the bulk of the wick. Generally, the end of the wick opposite of the end immersed in the fluid is exposed to air, and the fluid may evaporate from the surface of the wick broadcasting the fragrance into the space around the air freshener device.
However, isotropic wicks used in such air freshener devices and similar applications have several drawbacks. One of the more significant drawbacks is that when an isotropic wick is used to dispense volatile air freshener solutions, the wick generally absorbs an amount of air freshener solution when it is placed in the container. When the wick has a large volume relative to the volume of the container, this may cause the level of liquid in the container to drop as it is absorbed into the wick. In transparent devices sold into the consumer market, such as an air freshener container made of glass or clear plastic, this often creates the negative perception that the consumer is buying a less than full container of air freshener.
Although a smaller diameter wick may at least partially resolve this problem, the surface area of the wick is reduced due to the smaller diameter, and the dissemination of fragrance may be impaired as a result of less surface area of the wick for evaporation.
Accordingly, there is a need for a wick that initially provides a desired amount of fluid displacement while providing sufficient wick surface area for fragrance dissemination. There is also a need for a wick that displaces an amount of fluid approximately equal to the amount of fluid it initially wicks, resulting in a neutral displacement.